Various overflow tanks and auxiliary holding tank systems are well known in the prior art and examples of these are disclosed in the U.S. Pat. Nos. 3,610,220; 3,520,329; 3,207,203; 3,129,747 and 1,732,505. However, none disclose a system adaptable to the problem of gasoline spillage or overflow at the fill situs of underground storage tanks at typical automobile service stations. Present filling methods involve parking a transport vehicle adjacent the fill pipe of an underground storage tank, attaching the transport vehicle's flexible hose (connected to the transport tank through a valve at a control panel on the transport vehicle) to a fitting at the accessible, ground level, upper end of the underground storage tank fill pipe. The vehicle mounted valve is then opened and the storage tank is filled. When the storage tank has been filled, the valve is closed and the hose is disconnected from the fill pipe. The gasoline filling the hose spills and runs off into the area around the fill pipe. Further, since the fill pipe is full, there is spillage at the fill pipe as the hose is disconnected and the fill pipe cap is reinstalled. Deliveries to such storage tanks are made weekly, or more often if necessary, and the accumulation of spilled gasoline disperses through the sand conventionally used as a backfull for buried storage tanks. The accumulated spillage may then be carried away by subsurface water movement to contaminate sewers and basements and is an obvious hazard.
The apparatus of the present invention provides a means for retaining the gasoline filling the delivery hose by directing it to a dump tank which is automatically drained into the storage tank as gasoline is pumped therefrom in normal service station operation.